Blood pressure measuring apparatus



Jan. 13, 1953 w, A, BAUM 2,625,153

BLOOD PRESSURE MESURING APPARATUS Filed Dec. 14, 1949 INVENTOR I| WILLIAM A.'BAUM 7 bh mal/9mm ATToRNEY5 Patented Jan. 13, 1953 BLOOD PRESSURE MEASURIN G APPARATUS William A. Baum, Forest Hills, N. Y., assignor to W. A. Baum Co. Inc., New York, N. Y., a corporation of New York Application Decemberlfl, 1949, Serial No. 132,823

8 Claims. (Cl. 12s-2.05)

This invention relates to apparatus for the measurement of venous pressure.

Venous pressure is most conveniently measured by establishing a hydrostatic connection with the blood mass within the vein. Devices for the measurement of venous pressure on this principle have been proposed heretofore, as in an article of G. E. Burch and Travis Winsor in the Journal of the American Medical Association, vol 123 at page 91. Instruments of this type include a hypodermic needle to be inserted into the vein of which the pressure is to be measured, a transparent observation tube connected to the needle, and a manometer pneumatically connected to the observation tube. The motion of a short column of sterile fluid in the observation tube indicates the presence of pressure differentials between the blood in the vein and the air in the manometer. An expansible bellows connected to the manometer is employed to control the motion of the uid in the tube. When by manipulation of the bellows the fluid column is brought to rest, a constant hydrostatic pressure exists at all points between the needle and the surface of the manometer reservoir, and the venous pressure may be read from the manometer.

These instruments have been unsatisfactory in use however because of the difficulty in controlling properly the volume of air in the bellows and the initial height of the fluid column in the observation tube. To take a measurment of the pressure Within the vein, a suitable quantity of a sterile solution must be drawn into the hypodermic needle and observation tube before the needle is inserted into the vein. This provides a sterile buifer between the blood in the vein and the measuring apparatus, the column of fluid at the same time serving to communicate the pressure in the vein to the manometer and to provide an indication of equilibrium. In addition it is desirable, especially in a portable instrument, to be able to clear the manometer tube of air bubbles which may work into it, by drawing the column part-way down without entirely releasing the pressure in the observation tube. Each of these operations requires selectively opening separate passages from the bellows to the observation tube and to the manometer reservoir. During the actual measurement, on the other hand, the bellows must be connected both to the reservoir and to the tube. My invention provides an improved apparatus for the measurment of venous pressure in which these separate operations may be conveniently and rapidly carried out. It also provides an instrument employing a wet or tube type manometer, with its accompanying accuracy, but of compact and portable construction. To this end the manometer tube is jointed and supported in a frame which may be folded upon itself but which provides a watertight connection between the two sections when in extended condition,

My invention will be described with reference to the accompanying drawings in which Fig. 1 is a partially cut-away perspective view of an instrument according to my invention as used in the measurment of venous blood pressure, the manometer tube being in extended position for the measurment of maximum pressures;

Fig. 2 is a side elevation of the bellows, valve and control therefor in the instrument of Fig. 1; Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a section on the line 4-4 of Fig. 2;

Fig. 5 is a view similar to Fig. 3 but with the valve in its first position, certain elementsof the valve below the section line being shown in dotted lines;

Fig. 6 is a view similar to Fig. 5 but showing the valve in its second position;

Fig. 7 is a view similar to Fig. 5 but showing the valve in its third position, and

Fig. 8 is a partial perspective view of the instrument :of Fig. 1 in partially folded condition.

In Fig. 1 an embodiment of my invention is shown as it appears during the taking of a venous pressure measurment. The instrument, apart from the observation tube and hypodermic needle, is contained in a stand generally indicated at 3. For portability, provision may be made in the top of the stand for stowage of the observation tube 5, needle 1 and of a flexible tube 9 for connection of the observation tube with the manometer. A base II contains the reservoir I3 of an open tube manometer I 5 whose tube I1 extends up the front face I9 of the instrument. The reservoir is closed except for a filler plug 2I and an air connection 23 to the valve 25, the tube I'I extending down well below the normal liquid level in the reservoir and being open to the atmosphere at its upper end 21,

The venous pressure is communicated through the needle, observation tube and connecting tube to the surface of the manometer reservoir via a three-position valve 25, controlled by a lever 29 projecting from the base of the instrument. The valve has three ports, 3|, 33, 35 connecting respectively to an extensible bellows 3l, to the reservoir I3 (through a tube 23) and to the observation tube and needle (through tubes 9 and 39). The bellows may consist of a rubber bag 4l (Fig. 2) held between a support plate 43 and a shoe 45 actuated by a thumb screw 41. It serves alternately to aspirate and to pressurize the needle 1 and the manometer 15. The thumb screw passes through a nut 49 aflixed to a removable plate 5| forming part of the side Wall of the instrument.

The construction rof'the valve 25 is further illustrated in' Figs. 2"-7. The cylindrical valve body includes a bore 32 (Figs. 2 and 3) which com.- municates with the port 3l, and two additional bores 34 and 36 communicating respectively with' the ports 33 and 35 respectively. These bores, parallel to the axis of the valve -body,'are Acentered on a circle concentric with" the valve`body. Below the valve body 25 is aflixed a circular plate 53 rotated by means of the lever 29fjourr'ialed.inVv

the base and provided with a key 3D which en gages the plate 53 whenthe valve is assembled into the stand. As seen in Fig. 4, the plate 53 has formed in its upper surface a circumferentialv passage 5l.' This'passage is concentric with the plat`e53 and has the sameradius as thel circle onwh'ich are formed the bores 32, and 35, so asto communicate with them. The passage 6l however extends only through some 270, so that by rotation of the plate one or the other ofthe boresli and' 35v may be shut off from the passage Sl (Figs. 5, 6). Conversely, the circumferential extentof the passage 5| is greatenough so that all three of the bores 32, 3d and 35 may beexposed to the passage at once, as shown in Fig. 7. With the val-ve in the position shown in Fig. 5; passage 5i connects bores 32 and 3&5, establishing a connection between the bellows 31 and the manometer reservoir (from bellows 31 via port 3l, bo're 32, passage 5l, bore 34, port 33, and tube 23). With the valve in the position shown in Fig. 6, passage 5i connects bores 32 and S5, establishing aconnection between bellows 31 and Vobservation tube 5 (from bellows 31 via port 3l, bore 32, passage 6i, bore 35, port 35, and tubes Eiland 9). With thevalve in the position shown in Fig. '1, passage 6i connects together the three bores 32, 34; and 3E, thus interconnecting the the reservoir i3. It is held in position infront of acalibrated scale 15 on the front face I9 of the instrument, and is stressedtoward the reservoir` by means of a crosspiece 88 tting over a shoulder at its upper end, as shown in Fig. 8. The'upper end of the section H Vhas a'. shoulder 12 formed thereon upon which fits a complementary protrusion 13 formed on the lower endo the upper section 13. Ther section 13 is mounted on a hinged frame 19 in front of a scale 15 (affixed to the frame) which is continuous in its graduations with those of the scale 15 when the frame 19 is in upright position as shown in Fig. l. Crosspieces 81 and 9i similar to the crosspiece 88 are affixed' to the ends of the frame 13 and form bearings in which the section 13 is limite-d to motion parallel to its own length. The frame 19 may' then be lifted into upright position as shown in Fig. l or folded back as shown in dotted lines. A shoulder 83 at the upper end of the tube 13 carries a spring 85 which bears against the crosspiece 81, urging the section 13 in the general directionof the hinges so that in the position show-n in Fig.- l the two sections are stressed together to formawatertight connection at'tlieir point of junction.- A collar 89"`above the crosspiece limits the motion of the section 13 under the influence of the spring when the frame 19 is in folded position. Detents, as at 90, are provided in the stand to hold the frame 19 in either upright or folded position. The lower section 1| of the tube can be readily made of three hundred millimeters in length or more, and sui'- ces for manymeasurements. Where unusually highv pressures are encountered, the upper section may be brought into use as illustrated in Fig. 1.

Preliminary to taking a blood pressure measurement with the apparatus of my invention, the connecting tube Sis aixed to a nipple 40 in the wall of th'e stand 3; The nipple connects through a short lengthY of ilexible tube 39 to the port 35 in thevalve; A sterile observation tube having a needleaixed is then connected to the free end of the tube 9.

To prepare the instrument for the taking of a bloodv pressureimea'surement, the control lever 29 is turned to bring theV valve to the position shown in Figure', in which the bellows is' connected to the observation tube and needle only. With the valve in this position the thumb screw 41 is drawn all the way out'and then returned a few' turns so as to leave the bellows distend'ed by almost but vnot quite the maximum amount.

Should therev be bubbles in the water column ofthe manometer tube, they may be removed by setting the valve in the positionV of Fig. 5, connecting the bellows to the reservoir. By retract ing the thumb screw, theA bellows is distended farther and the Water column is drawn down into the reservoir where the bubbles come to the surface.

The vvalve should then be returned to the position of Fig. 6 and the thumb screw restored to its formerv position with the bellows almost but not quite completely distended. The end of the needle is dipped into'an ampule of a sterile solution such as 21A; percent sodium citrate, and a small quantity of the solution is drawn into the observation tube by retracting the thumb screw 41. Sui'hcien-t solution is drawn into the tube to bring the meniscus of the solution up into the central portion thereof, which may be engravedV with reference marks 6;

The` valve 25- is now shifted to the position shown in Fig. 7', in which the bellows is connected bothto the observation tube and to the manometer, thus forming a connection between thesetwo. The needle is inserted into thefveln whose pressure isto be-rneasured, the vein. being preferably at heart level.. The pressurewithin the vein is balancedY by manipulation ofthe thumb screw 41 to prevent the meniscus on the column of sterile solution from reaching the tubing Slat the top of the observation tube. Care should likewise be taken not to compress the bellows so far as to cause the entire column of solution to be discharged into-the vein.

By further control of thethumb screw the meniscus. on the iiuid column may be held in-.stationary position for. a brief period of time until it has'been brought permanently to. rest. The venous pressure mayrthenbe read from the height of thewater column in the manometer tube. To compensate for the capillary of the observation tuber it should. be: soi held that the meniscus therein'` standsA above "the point of entry' ofA the needleinto. the Vein by` a' distance equal to the capillarity of.. the vobservation: tube. By proper control the blood 'in'. the: veinis. prevented from entering either the needle or the observation tube, and the amount of sterile solution injected into the vein is held to a minimum.

After the pressure reading has been taken, the valve is returned to the position of Fig. 5, thus shutting-ofi the connection between the bellows and the water reservoir, and the needle is withdrawn from the vein.

I claim:

1. In an instrument for the measurement of venous blood pressure including a hypodermic needle connected to a pneumatic tube, a manometer and an extensible bellows for alternately aspirating and pressurizing lthe needle and manometer, a three-position valve adapted selectively to pneumatically connect the bellows with the needle, with the manometer, and with both, said valve comprising a valve body having three parallel bores disposed on a circle, a plate removably afxed to the valve body for rotation in a plane perpendicular to said bores about the center oi said circle, and a circular channel formed in the surface of the plate adjacent the valve body concentric with said circle and having the radius thereof, said channel extending through an arc of less than 360 and greater than the least arc encompassing said three bores.

2. In an instrument for lthe measurement of venous blood pressure including a hypodermic needle connected to a pneumatic tube, a manometer and an extensible bellows for alternately aspirating and pressurizing the needle and manometer, a three-position valve adapted selectively to pneumatically connect the bellows with the needle, with the manometer, and with both,

said valve comprising a valve body having three parallel bores opening onto a surface of said Valve body, a plate removably aixed to the valve body for motion over said surface, and a channel formed in the surface of the plate adjacent the valve cody, said channel being adapted to connect one of said bores alternately with the other two of said bores and with both, according lto the relative position of the plate and valve body.

3. In a blood pressure measuring instrument including a manometer for the measurement of venous blood pressure, a manometer tube having upper and lower sec-tions, a hinged frame supporting the upper section and a calibrated scale associated with the upper section, and spring means in said frame for stressing together said upper and lower sections when in parallel position.

4. In an instrument for the measurement of venous pressure, a stand, a manometer supported in the stand, a jointed tube ior the manometer having a lower section and an upper section for occasional connection to 'the lower section, said upper and lower sections having complementarily tting ends, a frame hinged to the stand for support of the upper section, and spring mounting means associated with the upper section urging the same into a watertight connection with the lower section when the frame is in raised position.

5. In an instrument for the measurements of venous pressure, :a stand, -a reservoir type manometer supported in the stand, a jointed tube for the manometer having a lower section aiiixed to the manometer reservoir and an upper section for occasional connection to the lower section, said upper and lower sections having complementarily tting ends, a frame hinged to the stand for support of the upper section, yand spring mounting means associated with the upper section urging the same into a watertight connection with the lower section when the frame is in raised position.

6. In an instrument for the measurement of venous pressure including a manometer and a jointed rnanorneter tube having a lower section supported in a stand and an upper section adapted to be connected to the lower section for the measurement of pressures higher than those measurable with the lower section alone, said lower and upper sections having complementarily iitting ends adapted to provide a watertight joint therebetween when the sections are stressed together in aligned relation, -a mounting for said upper section comprising ya frame hinged to the stand, bearings in said frame adapted to vsupport the upper section, a collar formed on the upper section adjacent one of s-aid bearings, a spring stressed between said collar and said one bearing, said spring urging said upper section in the direction of said hinges, and means to limit the travel of said upper section under the inuence of said spring,

7. In an instrument for the measurement of venous pressure including a manometer Iand a jointed manometer tube having 1a lower section supported in a stand :and an upper section adapted to loe connected to the lower section for the measurement of pressures higher than those measurable with the lower section alone, said lower and upper sections having complementarily fitting ends adapted to provide a watertight joint therebetween when the sections are stressed together in aligned relation, a mounting for said upper section comprising a frame hinged to the stand, bearings in the frame adapted to limit said upper section in its motion relative to the frame to motion parallel to the length of the said upper section, a collar formed adjacent the end of said upper section remote from the hinges, a spring stressed between said collar 'and one of said bearings, and, means to limit the travel of said upper section relative to said frame under the iniiuence of said spring.

8. In venous pressure measuring yapparatus including a hypodermic needle, ya manometer, a pneumatic connection between the needle and monometer `and a three-position valve for controllably blocking said connection, an extensible bellows adapted :alternately to aspirate and to eXpirate the needle and the manometer via the valve, said bellows comprising a distensible bag connecting with the valve, a support for the bag, a shoe adapted to constrict the bag against the support, and means to advance the shoe relative to the support.

WILLIAM A. BAUM.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 580,822 France Nov. 17, 1924 650,567 France Jan. 10, 1929 799,505 France June 15, 1936 827,365 France Apr. 25, 1938 OTHER REFERENCES Article by Burch and Winsor, in the Journal of the American Medical Association, vol. 123, pages 91-92. (Copy in Scientific Library.) 

